To estimate carbon emissions (as CO2) for the default house consumption (Typical House), we use regional emission factors for electricity, and national emission factors for fuel-fired appliances and equipment. For electricity, we developed regional emissions factors using total emissions for fossil steam generation units (US DOE 1996), divided by net generation in each census division. We then added 8% transmission and distribution losses. Finally, we scaled up to account for the additional generation (roughly 2% nationally, but different regionally) that is associated with combustion turbines and internal combustion engines. This approach assumes that the combustion turbines and IC engines have, on average, the same emissions per kWh as the other fossil-steam plants. The resulting values are annual averages for all electricity generated within that region. The resulting emission factors are shown in Table 28.
 This methodology accounts for zero-emission generation from hydro, nuclear, and renewables.